Field of the Invention
The present invention generally relates to MOSFET circuits and more particularly to fast switching in MOSFETs.
Fast switching in high voltage or high power semiconductors is desirable because a semiconductor switch dissipates the most power during switching, i.e., while it is in a state between fully "off" and fully "on". By minimizing switching time and, therefore, heating, the semiconductor can be allowed to switch more power. Fast switching is also needed in the formation of fast rising pulses for a variety of applications.
A primary limitation to fast switching in MOSFETs is source lead inductance. Heavy load currents combine with source lead inductance to form a large voltage drop in the source circuit, which subtracts directly from the gate drive. Since the source lead inductance is always deleterious, it should be minimized within the physical constraints of the MOSFET package or die bonds, but it cannot be made equal to zero.